JP3123136B2 - Surface emitting semiconductor laser, array thereof, surface emitting light emitting diode, array thereof and surface emitting pnpn device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-emitting type semiconductor laser in which the controllability of the polarization direction is good and stabilized, a semiconductor laser array in which the polarization directions of individual elements are aligned, and a polarization direction dependence. The present invention relates to a light emitting diode and a light emitting diode array in which polarization directions of individual elements are aligned.

[0002]

2. Description of the Related Art In recent years, research and development of a surface-emitting type semiconductor laser for extracting light in a direction perpendicular to a substrate surface has been actively performed as an application to an information processing field such as a light source for an optical disk and an optical computing application. Surface emitting semiconductor lasers that operate continuously at room temperature are also disclosed in Japanese Journal of Applied Physics (A. Ibaraki et al.
Jpn. J. Appl. Phys. Vol. 28 (19
89) L667).

In a semiconductor laser that extracts light output from the normal end face direction, the mode selectivity of end face reflection is remarkable due to the waveguide structure, so that the semiconductor laser oscillates stably in the TE mode. Oscillation with linearly polarized light even in a surface-emitting type semiconductor laser is described in Journal of Quantum Electronics (K. Iga).
et al. IEEE J.I. Quantum Elec
tron. Vol. QE-21 (1985) p. 663)
It is reported that the polarization direction is transmitted in the [110] direction or the [1, -1, 0] direction, according to the Japanese Journal of Applied Physics (M. Shim).
Izu et al. Jpn. J. Appl. Phys
s. Vol. 27 (1989), p. 1774), but the surface-emitting type semiconductor laser is isotropic with respect to the beam vertical direction, so that the polarization direction cannot be uniquely defined and is unstable. In some cases. Attempts have been made to control the polarization direction by depositing Si on one side of the dielectric multilayer film, which is a p-side reflector, and providing a loss (Preliminary lecture of Spring 1991 Joint Lecture on Applied Physics). Vol. 31a-D-2).

[0004] A normal light emitting diode has no polarization direction dependence and emits light with a random electric field vector. For this reason, it is quite difficult to control the polarization direction.

[0005]

In the conventional surface-emitting type semiconductor laser, the anisotropy due to the roughness of the crystal surface and the stress,
Since the polarization direction is determined by the combination of the non-parallel mirror surface, the mesa shape anisotropy, and the anisotropy of the deposited film, it has been difficult to control and stabilize the polarization direction. [11
The method of controlling the polarization direction by providing a loss in either the [0] direction or the [1, -1, 0] direction requires a complicated process, and the beam shape may be deformed from a circular shape. .

In the conventional light emitting diode, the electric field vector of the emitted light is random, and the polarization direction does not depend on the vertical direction of the emitted light.

Further, in a surface emitting element array in which surface emitting elements whose polarization directions are not controlled are integrated on the same substrate, there is a high possibility that the polarization directions of individual elements are different.
It is difficult to provide a surface emitting element array in which the polarization direction is aligned in one direction.

An object of the present invention is to use a crystal having polarization direction dependency in the active layer, so that the polarization direction can be easily controlled and a complicated manufacturing process such as providing a loss in one direction of the element can be achieved. A surface-emitting semiconductor laser and a surface-emitting light-emitting diode that do not require and do not introduce a structure that deforms the beam shape, and a polarization in which the surface-emitting semiconductor laser or the surface-emitting light-emitting diode is integrated on the same substrate It is an object of the present invention to provide a semiconductor laser array and a light emitting diode array, or a surface emitting pnpn element, with aligned directions.

[0009]

According to the surface emitting semiconductor laser of the present invention, the semiconductor substrate has a [-] plane orientation of [-].
A semiconductor layer including an active layer having a natural superlattice formed on a semiconductor substrate inclined in the [1,1,0] or [1, -1,0] direction, and having a resonator perpendicular to the substrate surface; It is characterized by having.

Further, a semiconductor laser array according to the present invention is characterized in that the above-mentioned surface-emitting type semiconductor laser is integrated on the same substrate.

The surface-emitting type light emitting diode of the present invention has a natural orientation on a semiconductor substrate whose plane orientation is inclined in the [-1,1,0] or [1, -1,0] direction from the (001) plane. The semiconductor device includes a semiconductor layer including an active layer in which a superlattice is formed, and has a structure in which light is extracted from the front surface or the back surface of the substrate.

Further, a light emitting diode array according to the present invention is characterized in that the above-mentioned surface emitting light emitting diodes are integrated on the same substrate.

Further, the active layer of the surface emitting pnpn element has a natural superlattice or is an array thereof.

[0014]

In the GaInP or AlGaInP epitaxial growth layer, [-1,1,1] or [1, -1,
1] It has been reported that a natural superlattice having an ordered periodic structure is formed in the [1] direction (for example, Applied Physics Letters (Gomyo et a).
l. Appl. Phys. Lett. Vol. 50 (1
987) p. 673)). In a semiconductor in which a natural superlattice is formed, the electric field vector of light emission between the lowest levels is (-1, 1, 1) or (1,-) in which a natural superlattice is formed.
(1) The in-plane bias is due to the physical review letters (A. Mascarenhas et al.
Phys. Rev .. Lett. Vol. 63 (198
9) p. 2108).

The surface-emitting type semiconductor laser of the present invention has an active layer in which a natural superlattice is formed, and an optical output is taken out in a direction perpendicular to the substrate surface.
When the substrate having the 1) plane is used, the electric field component of the spontaneous emission light equal to or lower than the oscillation threshold value is [11, 1, 0] compared to the [-1, 1, 0] direction.
0] direction increases. Since a semiconductor laser oscillates with a polarization in the direction of a large gain, the surface emitting semiconductor laser of the present invention emits with a polarization in the [110] direction. In the surface-emitting light emitting diode of the present invention, the luminous efficiency of light polarized in the [110] direction is increased.

In an epitaxially grown layer formed on a semiconductor substrate whose substrate crystal plane orientation is inclined in the [-1,1,0] or [1, -1,0] direction from the (001) plane, the order of the natural superlattice is obtained. And a natural superlattice is formed most strongly on a semiconductor substrate inclined from 4 ° to 6 °. This (00
1) The polarization selectivity is further enhanced by using a substrate inclined from the plane, and a surface-emitting type semiconductor laser can efficiently emit light having an electric field vector in the [110] direction, and thus can oscillate. It also reduces the threshold current. In the case of a surface emitting type light emitting diode or a surface emitting type pnpn element, the polarization direction dependence in the [110] direction is further increased.

Further, in the surface-emitting type semiconductor laser, the surface-emitting type light-emitting diode, or the pnpn element array of the present invention, the polarization direction of each surface-emitting type element is set to [110]. Can be aligned in any direction.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the surface emitting semiconductor laser according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a surface-emitting type semiconductor laser of the present invention, and FIG. 2 is a view for explaining a manufacturing process thereof.

First, as shown in FIG.
An n-type (Al) having a thickness of 2.0 μm is formed on an As (001) substrate 1.
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P cladding layer 2,
2.0μm undoped Ga _{0 thick. 5} In _{0. 5} P active layer 3,1.0μm thickness of p-type _{(Al 0. 7 Ga 0.} 3)
_{0. 5} In _{0. 5} P cladding layer 4, 20 pairs of p-type (Al
_{0. 1 Ga 0. 9) 0} . 5 In 0. 5 P / (Al 0. 7
_{Ga 0. 3) 0. 5} In 0. 5 P DBR multi-layer film 5,
0.1μm thick p-type Ga _{0. 5} In _{0. 5} and the P hetero buffer layer 6,0.5Myuemu p-type GaAs cap layer 7 having a thickness laminated grow. p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 I
_{n 0. 5 P / (Al} 0. 7 Ga 0. 3) 0. 5 In
_0.5 The thickness of the P DBR multi-layer film 5 is λ with respect to the oscillation wavelength
/ 2 cycle. Crystal growth is under reduced pressure MOVPE
Method was used. The growth conditions were a temperature of 660 ° C., a pressure of 70 Torr, and a group V material supply amount / group III material supply amount ratio (V / III ratio) of 150 so as to form a natural superlattice. The raw material is trimethyl aluminum (TM
A), triethylgallium (TEG), trimethylindium (TMI), arsine (AsH ₃ ), phosphine (PH ₃ ), and disilane (Si ₂ H) as an n-type dopant
₆ ), dimethyl zinc (DMZ) as p-type dopant
Was used.

After a 7 μm diameter SiO ₂ mask 12 is formed on the wafer by lithography, FIG.
As shown in, p-type _{(Al 0 .7 Ga 0. 3} ) 0. 5 I
In order that the n _0.5 P cladding layer 4 remains about 0.3 μm,
P-type GaAs cap layer 7 by wet etching,
p-type _{Ga 0. 5 In 0. 5} P hetero buffer layer 6, p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 In 0. 5 P / (Al
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P DBR multi-layer film 5, p-type _{(Al 0. 7 Ga 0 .3} ) 0. 5 In 0. 5 P
The cladding layer 4 was removed.

Next, as shown in FIG.
_{Using the} mask ₂ as a mask, an n-type GaAs block layer 8 having a thickness of 3 μm was selectively grown by the reduced pressure MOVPE method. The growth conditions were as follows: temperature 650 ° C., pressure 70 Torr, V / III ratio 4
It was set to 5. As a raw material, trimethylgallium (TM
G), arsine (AsH ₃ ), and disilane (Si ₂ H ₆ ) as an n-type dopant. After growing the n-type GaAs block layer 8, the SiO ₂ mask 12 is removed.

Next, an n-electrode 10 is formed, and FIG.
As shown in FIG. 5, after the resist 13 applied on the n-electrode is patterned by photolithography into a circle having a diameter of 200 μm so that the p-side circular mesa is located at the center, the resist 13 is used as a mask to form the n-electrode. 10 and the n-type GaAs substrate 1 were removed by wet etching to form a window for light emission. After removing the resist 13, the p-electrode 11
Was deposited.

[0023] n-type removal of the n-type GaAs substrate as shown in FIG. _{2 (e) (Al 0.} 7 Ga 0. 3) 0. 5 In
_A dielectric multilayer mirror 9 was formed on the 0.5 P cladding layer 2. The dielectric multilayer reflector 9 and the p-type (Al _0.1 G
_{a 0. 9) 0. 5} In 0. 5 P / (Al 0. 7 Ga
_0.3 ) The _0.5 In _0.5 P multilayer film 5 forms a resonator. Finally, each element is separated by cleavage, and p
The electrode side was mounted on a heat sink by fusing.

The thus obtained surface emitting semiconductor laser of this embodiment has a polarization direction of [110] at the time of oscillation.

The substrate plane orientation is shifted from the (001) plane by [-1,
1 on an n-type GaAs substrate tilted 6 ° in the [1,0] direction.
A surface-emitting type semiconductor laser having the same structure as described above was formed. This surface emitting semiconductor laser was stably polarized in the [110] direction, and the oscillation threshold current was reduced by 15% as compared with the surface emitting semiconductor laser using the (001) substrate.

FIG. 3 shows a structure of a semiconductor laser array in which nine surface emitting semiconductor lasers are integrated on the same substrate at an interval of 400 μm. The structure of each surface emitting semiconductor laser is shown in FIG.
Is the same as The polarization directions of the individual laser beams of this semiconductor laser array are aligned in the [110] direction.

Next, an embodiment of the surface emitting type light emitting diode of the present invention will be described with reference to the drawings. FIG. 4 is a cross-sectional view of the surface-emitting light emitting diode of the present invention, and FIG. 5 is a view showing a manufacturing process thereof.

First, as shown in FIG.
An n-type (Al) having a thickness of 2.0 μm is formed on an As (001) substrate 1.
_{0. 7 Ga 0. 3)} 0. 5 In 0. 5 P cladding layer 2,
2.0μm undoped Ga _{0 thick. 5} In _{0. 5} P active layer 3,5.0μm thickness of p-type _{(Al 0. 7 Ga 0.} 3)
_{0. 5} In _{0. 5} P cladding layer 4,0.1Myuemu p-type Ga _{0 thick. 5} In _{0. 5} P hetero buffer layer 6,0.5μ
An m-thick p-type GaAs cap layer 7 was stacked and grown. The crystal growth method, growth conditions, and raw materials are the same as those of the above-described surface-emitting type semiconductor laser. As shown in FIG. 5 (b), a 30 μm-diameter hole was formed on this wafer by lithography.
An O ₂ insulating film 12 was formed.

Next, an n-electrode 10 is formed, and FIG.
As shown in FIG. 3, a resist 13 applied on an n-electrode is coated with a p-side SiO ₂ insulating film 12 by photolithography.
Then, the n-electrode 10 and the n-type GaAs substrate 1 were removed by wet etching using the resist 13 as a mask to form a window for light emission. As shown in FIG. 2D, after removing the resist, a p-electrode 11 was deposited. Finally, each element was separated by cleavage, and the p-electrode side was mounted on a heat sink by fusing.

The surface emitting light emitting diode of the present invention thus obtained has a high polarization direction dependency, and 65% or more of the emitted light is polarized in the [110] direction.

The substrate plane orientation is shifted from the (001) plane by [-1,
4 on an n-type GaAs substrate tilted 6 ° in the [1,0] direction.
A surface-emitting light emitting diode having the same structure as that of Example 1 was formed. In this surface-emitting light emitting diode, the polarization direction dependence is higher and 75% or more of the emitted light is polarized in the [110] direction as compared with the surface-emitting light-emitting diode using the (001) substrate.

FIG. 6 shows the structure of a light emitting diode array in which nine surface emitting light emitting diodes are integrated on the same substrate at 400 μm intervals. The structure of each surface-emitting light emitting diode is the same as that of FIG. The polarization direction of each emitted light of this light emitting diode array is aligned in the [110] direction.

As one embodiment of the surface-emitting type pnpn device of the invention, n- (Al _x Ga.sub.x) is formed on an n-type GaAs substrate.
_1-x ) _0.5 In _0.5 P (0 <x <1), P- (A
_{l Y Ga 1 -.. Y} ) 0 5 In 0 5 P (0 <Y <x <
1), an undoped _{Ga 0. 5 In 0. 5} P active layer, n-
_{.. (Al Y Ga 1 -} Y) 0 5 In 0 5 P, p- (Al
_{x Ga 1 -.. x)} 0 5 In 0 5 P, to form a semiconductor layer made of p-GaAs, to form an electrode in the same manner as described above for the surface-emitting light-emitting diodes, it mounted. Even with this pnpn element, light emission highly dependent on the polarization direction was obtained. This element can be applied as a switching element or an optical function element. When an array is used, a pnpn element array having a uniform polarization direction can be obtained with good uniformity.

[0034]

According to the surface emitting semiconductor laser of the present invention, the polarization direction can be controlled stably and a complicated manufacturing process such as providing a loss in one direction is not required. Therefore, a highly reliable polarization-controlled surface emitting semiconductor laser can be obtained.

Further, the surface emitting type light emitting diode of the present invention has polarization direction dependency, and the direction can be controlled.

In a semiconductor laser array and a light emitting diode array in which these elements are integrated on the same substrate, the polarization directions of all the integrated elements can be aligned in one direction.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a surface emitting semiconductor laser according to the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the surface-emitting type semiconductor laser of the present invention.

FIG. 3 is a structural diagram of one embodiment of a semiconductor laser array of the present invention.

FIG. 4 is a cross-sectional view of one embodiment of the surface emitting light emitting diode of the present invention.

FIG. 5 is a diagram for explaining a manufacturing process of the surface-emitting light emitting diode of the present invention.

FIG. 6 is a structural view of a light emitting diode array according to one embodiment of the present invention.

[Explanation of symbols]

1 n-type GaAs substrate 2 n-type _{(Al 0. 7 Ga 0.} 3) 0. 5 In 0. 5 P
Cladding layer 3 undoped _{Ga 0. 5 In 0. 5} P active layer 4 p-type _{(Al 0. 7 Ga 0.} 3) 0. 5 In 0. 5 P
Cladding layer 5 p-type _{(Al 0. 1 Ga 0.} 9) 0. 5 In 0. 5 P
_{/ (Al 0. 7 Ga 0} . 3) 0. 5 In 0. 5 P DBR multi-layer film 6 p-type _{Ga 0. 5 In 0. 5} P hetero buffer layer 7 p-type GaAs cap layer 8 n-type GaAs block layer 9 Dielectric multilayer film reflector 10 n-electrode 11 p-electrode 12 SiO ₂ insulating film 13 resist

Continuation of front page (56) References JP-A-3-104292 (JP, A) JP-A-3-159289 (JP, A) JP-A-4-199589 (JP, A) JP-A-4-259263 (JP) , A) JP-A-4-273490 (JP, A) JP-A-4-340288 (JP, A) IEEE J.I. Quantum Electron. 24 [9] (1988) p. 1845-1855 (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 H01L 33/00

Claims (7)

(57) [Claims] An active layer having a natural superlattice formed on a semiconductor substrate having a semiconductor substrate plane orientation inclined in a [-1,1,0] or [1, -1,0] direction from a (001) plane. A surface-emitting type semiconductor laser comprising: a semiconductor layer including a semiconductor layer; and a resonator in a direction perpendicular to the substrate surface. 2. The semiconductor substrate has a plane orientation from a (001) plane.
A semiconductor layer including an active layer having a natural superlattice formed on a semiconductor substrate inclined in the [-1,1,0] or [1, -1,0] direction ; integrated collectively on the same substrate surface-emitting type semiconductor lasers having a cavity in a vertical direction against
Surface-emitting type semiconductor laser array, characterized in that the. 3. A surface-emitting type semiconductor laser array, wherein the surface-emitting type semiconductor laser according to claim 1 is integrated on the same substrate. 4. An active layer in which a natural superlattice is formed on a semiconductor substrate whose plane orientation is inclined in the [-1,1,0] or [1, -1,0] direction from a (001) plane. A surface-emitting light emitting diode, comprising: a semiconductor layer including a light emitting layer; and a structure for extracting light from the front surface or the back surface of the substrate. 5. A surface emitting light emitting diode array, wherein the surface emitting light emitting diodes according to claim 4 are integrated on the same substrate. 6. The semiconductor substrate has a plane orientation from a (001) plane.
An active layer having a natural superlattice formed on a semiconductor substrate inclined in the [-1,1,0] or [1, -1,0] direction and a pnp
A surface-emitting pnpn including a semiconductor having an n-type structure and having a structure for extracting light from a front surface or a back surface of the substrate.
element. 7. A surface-emitting type pn device wherein the surface-emitting type pnpn element according to claim 6 is integrated on the same substrate.
pn element array.